Pull head for broaching machines



Jan. 8, 1946. LAPQINTE I 2,392,747

PULL HEAD FOR 'BROACHING MACHINES Filed Aug. 23, 1945 2 Sheets-Sheet 1 IN VEN TOR.

Jl aamz Jan. 8, 1946.- F. J. LAPOINTE 2,392,747

PULL HEAD FOR BROACHING MACHINES Filed Aug. 25, 1943 2 Sheets-Sheet 2 I J3 INVENTOR.

Patented Jan. 8, 1946 PULL BROACH NG MACHINES j Francis 1-. Lapointe,v Ann Arbor, Mich, assignor to. American Breach & Machine Co.,Ann;.w;

Arbor, Mich, a corporation; of M Ghigan A1 1p'l i cation August 23, 1943, Serial 180,499,640

20 Claims.

This invention relatesto broaching machines and to broaches to be usedtherein, and it is partieularly concerned with means for mounting in such a machine a type of broach having teeth disposed only at one. side of its axis, as, for example, in akeyway broach, or at least with the teeth so arranged that in setting up the work it is necessary to have. the broach-positioned with its teeth in a certainrelation to. theaxis of the bore in the work piece.-

One object of the invention is to provide a new andimproved pullhead-for a breaching machine.

Another object of the. invention is to provide a pull head engageable. with ,a broach having a shank-ofsubstantially the same cross section as thebody of the broach with a minimum reduc tion-of that cross section forming a notch at oneside of the shank. for engagement with the pull head.

A further object isto. provide a pull head for a broach having cutting teeth of non-circular. cross section and in which the shank of the broach is formed atonly one side for engagement with the pullhead, thus determining theposition.

of the. broach teeth with respect to. the axis 01 thebroach'. 7

It is also an object or, the invention to provide a pull. head f0r=a broach oi non-circular cross.

section, having means which mayv b quickly operated to engagethe shank. of thebroachor to release it, without rotating thebroach about its axis.

More specifically, it is an object of theinvention to provide a pull. head with means forengagement' with broaches. of rectangular cross-75cction...0r other non cylindrioal shapes, andwith.

means for adapting th pull head to a relatively widerange. 0f slzesof broaohshanks by simple adjustments, and they use of certaininterchangeable parts.

Otherobjects and advantagesof the invention will appearfrom thefollowing description taken.

in connection with the. drawingsin which:,

Fig. l is asideelevation of' a pull. headshowing a portionv of akeyway broachsecured thereinin accordance, with this invention.

Fig. 2 is a perspectiveview of the pull headon .a larger scale, showing. a fragment or the shank of the, broach removed from .the head.

Fig. -3 is a sectional view taken. substantially as indicated at line-3-.-3 on Fig. 1

Fig. 4 isa section at. aplanezsubstantially per-- pendicular to that at which-Fig.- 3 is taken, this sectionloeingtaken as indicated at line. 41-4 on Fig. 2.

' in Fig, 10, together with means adapting it ior ame plane as. Fig. 34;, but; illustrating the pull" head withits operating cam block replaced; by

a deeper. cam block' to secure engagement with a broach shank of smaller cross-section.

Fig, 7 is a detail perspective V 1GW of one of the cam blocks.

Fig. 8 is a detail perspective view ogf-the clutch;

bar for the-pull head.

Fig. 9 is-a fragmentary p rspective view of a;

special form of broach shank which'the pullheadis adapted to receive,

Fig.,y1 0 is a fragmentary perspective'view of another; special form of broachshankadapted to be fitted in the pullhead.

Fig. l1 is a cross-section of th'eshank-shown in Fig. 9; indicating'means for holdin it-in; the pull head.

Fig. 12 is a cross-section of the shank shown use in the un head of this invention. a

Fig. 13 is a side elevation showing afragment of a-keyway broach having a threaded shank,-

together with an adapter applied thereto for use inthepull headof this invention;

WhiIe I- have shown in the drawings-and will herein describe in detail, certain preferred-embodiments of my invention, it is to be understood.

that I'do not therebyintend to limit theinvenqtion to the specific forms disclosed; .but .aim: to coveraall modifications and alternative construc-.

tions falling within the spirit and scope of the;

invention as expressedin the appended claims.-

Heretofore, in lihGgCOILSbIllCfiiOIl of keyway breaches and certain other broaches of non.-' circular. cross=section, 101 having teeth.- provided onlyat one or two sides of the axis. it has been customary to make the-broach: with athreaded' shank for-connection; with the pull head'of' thebroaching; machine, -In substantially all. casesthis wou d .result n so e r duct on f g ss sectionin order to providerarylindrical portion of the shank to be threaded. -Frequently', the insertion and removal of such a breach Was-a slow and awkward operation; requiring the oper ator to handle thelsharp corners and cutting:

edges-of the broachsometimes injuring himseli. in turning it about its axis-iorscrewing it into.

the. pull head or unscrewin it therefrom,

thermore, in. forming athreadedshank on the end'off a breach bar. or, re tangular. cross-section. it ha alwa s; een .cl iq lt t etthe v i dnical.

portion, exactly ..centered between two parallel V The present invention provides an arrange- 1 ment which does not require any appreciable reduction in cross-section'of the shank, and which permits the shank to be quickly inserted or removed without rotation about its axis, and without any strenuous handling on the part of the operator.

As shown in the drawings, the pull head illustrating this invention includes a threaded shank I by which it is coupled to the ram or crosshead of a broaching machine, and this shank may carry a lock nut 2 for securing it in position. The outer end of the shank is formed to constitute a portion of the pull head body, and in the position shown in the drawings this includes the bottom wall section 3. Side walls 4, 4 are bolted to. the part 3 and connected also byv dowels or'crosspins 5, 5. A top wall 6 is bolted to the sidewalls,

thus forming a receiving chamber or socket of rectangular cross-section into which the shank of the breach may be inserted.

It may be understood that a pull head of this typefis applicable either to a horizontally moving slide or to a' vertically movable slide of a broaching machine, butsince it is illustrated inrthe drawings in horizontal position, thevarious parts and features may be referred to as in the positions shown, whereas when such a pull head is mounted in a vertically movable slide, certain horizontal parts will be vertically disposed, and vice-versa. As shown in Fig. 2, the side walls 4, 4

are formed with vertical guideways I which en- 1 gage the end portionsof a horizontally disposed clutchbar 8 which floats on'compression springs- 9 and is vertically adjustable in the guideways 1. Any broach intended for use in this pull head is provided with a shank, such as thatpshown at I 0 in Fig. 2, having a notch II in its upper face, with a flat bottomwall and with sloping adjacent walls I 2, I2. Theunder side'of the clutch bar 8.is formed to fit the notch II and includes beveled or sloping faces I3, I3 'for engagingthe inclined surfaces 12, I2, as shown in Fig. 4.

The top wall 6 of the pull head is formed with 1 a guideway I4 in which there is mounted a, slide member I5 having an operating handle I6 which wall 6. A coil spring I8 is pocketed in the inner I9 projecting into the guideway from a cover plate projects through a clearance slot I! in said top 20 applied to the pull head adjacent its threaded shank I, as seen in Fig. 4. The under face of j the slide I5 carries a cam'block 2| having an inclined cam face 22 which is engageable with a correspondingly inclined face 23 formed in the the slide I5 is moved to its outer limit by the 7 force of the spring I 8, the cam block 2| acts as a wedge to force the clutch bar 8 downwardly into engagement with the notch I I 'of the broach lines in'Fig. 4, so that the springs 9 upon which 7 upper surface of the clutch bar 8. Thus, when,

the clutch bar 8 is supported, can lift the bar clear of the notch II and permit the shank of the-broach to be withdrawn from the pull head.

It may be understood that the slide or crosshead of the broaching machine to which the shank I of the pull head is secured, is usually provided with means for adjusting the axis of the pull, head within certain limits for proper alignment with the work on which the broach is to operate. The machine will also be provided with a suitable work support which, in most cases, will be adjustable transversely of the axis of movement of the broach so as to position the work accurately with relation thereto. The pull head itself is provided with adjustable gates or jaws 25, each secured to its outer face by means of a clamping bolt 26 inserted through a slot ZI'in the gate 25 so that these members may be adjusted laterally to provide an opening substantially equal to the width of the shank It) to properly position theishank as it is inserted be- I is lodged in the bottom of the chamber of the pull head so that the shank l0 rests directly upon this shim plate 30 and is thereby correctly positioned for operative engagement by the clutch bar 8. The shim 30 is held in place by bolts 33,

p 33 extending through the bottom wall of the pull head, and'for convenience the'additional shim platestl and 32 are carried by these bolts. If two plates instead 'of one should be required in the chamber of the pull head, as shown, for example, i'n Fig. 6, in which the plates 33 ands! are seen disposed under a broach shank 140 of smaller dimensions than the shank It, then the additional plate 32 will be carried under the heads 7 of the bolts 33, although this portion of the structure is not shown in Fig. 6. To permit this arrangement, each of the plates 39, SI and 32 is provided with two threaded holes 34, and two. larger clearance holes 35, the threaded holes 34,

34 being spaced apart by the samedistance 'as the bolts 33, 33, and the clearance holes 35,35

being also spacedapart by this distance but offset from the threaded holes. The uppermost shim plate will thenact as a nut engagingthe threaded ends of the bolts 33 while the bolts will pass through the clearance holes of the other plates.

Further adjustments to accommodate broach shanks of different dimensions are provided by supplyingtwo or three substitute blocks for the cam block 2I. Fig. 6 shows a cam block 4| replacing the block 2|, anddimensioned to force the clutch bar 8 somewhat farther down, so asto cause it to engagethe'shank 48, which is con-' siderably smaller than the shank I0. "It will" be understood that the adjustment of the gates, or jaws 25, 25 and the placement of a chosen number of shim plates in the chamber of the pull head provides only an approximate positioning of the particular broach in relation to the work, and

that the final adjustment will be made by means (not shown) by which the pull head may be moved support, or both. 7

Occasionally, a broach of unusual cross-section is employed, having teeth'at only one sideof the axis; or perhaps'at two opposite sides, sothat it is necessary-to position the broach accurately-in the pull head-with relation to the work, to insure that the teeth shall operate at exactl 'the right portion'of the bore therein. --The shank of such a broach is illustrated at 50 in Fig; 9, as being of square'cross-section, but intended to operate-with onediagonal of its cross-section-in a vertical 6| 'cuton its opposite sideywithia notch 62 be-' tween them, and. with inclined faces 63, 63 for en-1 gagement wi'ththe beveled edges I3 of the clutch bar.

Figf13 shows'a typical keyway' broach 1.8, as heretofore constructed, with a reduced and threaded cylindrical terminal H. .For adapting such abroach for use in the pull head of the;pres ent invention. I propose to supplyv an adapter shank 1.2 of rectangularcross-section, having a notch 13' to be engagedby the clutch bar 8 of the pull head. and having a threaded socket in one end-,at 14, to receive the threaded terminal H of the broach A series of fiveor six such adapt er shanksmaybe supplied with each pull head for :use with existing broaches' of. the old style, already in stock.-.

Ordinarily, at the end of the working stroke of. a broach; it is necessar to remove. it from the pull headso as toenter its shank throughtheibore of thetnext piece, of work to be operated upon. The release of the broach. shank. may be accomplished automatically in some cases .by proyiding an adjustable-tappet screw as, threaded. into the outer end of-theslide l andprojecting' therefrom for encounter with any suitable actuating mem berrby which the slide! 5 may be thrust to release position. at the; proper time in the. cycle of operation... For. example, in machines in which the pull head reciprocates vertically, it is commonto pro vide a fixture below the work t'able'or work support,.which is adapted to engage the lower end of the-broach and withdraw it from the pull head at the. proper time. the-upward strokeit will be pulled through the work-piece upon completion of the broaching operation, and the work will then either fall awayv from the work support or it can be removed manually. Then, as the pull headtravels downwardly in its idle stroke, thetappet screw-BU will strike the worksupport at the end of the downward stroke, causing the. slide [5 to be pushed into the pull head in a position to releasethe. clutch bar 8, andto allow .the shank of the broach to be withdrawn from the pull head by the'handling mecha nism mentioned, and not herein shown. In some. instances;..similar mechanism may be provided for a horizontally operated broach, such, as that shown in Fig. l. The work support 95! may be understood as a rigid portion .of the machine frame, and is shown provided witha bushing EH which carries a, flanged member 92, having'a,

work-supportinghorn 93 formed. with a slotlor guideway in which the toothed portion Ill of the If the broach does itswork on broach travels,v and fhavingia partially cylindrical portion. on which thework-piece Mill is supported.

during the 'broaching operation. After completion-of the work; the piece 100 will be removedfrom the supporting horn"93', a'nd at the 'end of" the return strokeof thepull head thetappet screw" will strike the :tab'le or work support v andthus release the shank'of the broach from the; pull head; as already described; permitting the. broach to be withdrawn while a new work-pieceais. positioned on the horn 93, through which-"the shank of the broach will be inserted.forreengages ment'in the pull head.

I claim as my invention:

1. A pull head for a broaching machine-have ing a chamber open at one end to receive a broacln shank, guideways in the opposite side-walls' 'of the chamber extending transversely -tl'ierieoffl a. clutch bar-extending across thecham-ber-with'its. end portions in said guideways, and means. for: moving said bar along the guideways for engag ing or disengaging a shoulder on the broachshank.

2. A pull head for a breaching machine having" a chamber openat one end to receivea broach I supports one side of said shank, a clutch mem" ber" movable in the pull head toward and from said .wall,1spring means normally urging said member away from: said wallg'and Wedge means adjustable in thepull head and operative against said clutchmember to move it toward saidwall and into'holding' engagement with the shank of the broach.

4. A pull head for a broachingmachinehav ing' a chamber open at one end" to receive a broach. shank, said chamberj having a wall which sup ports "one side of said shank,'gi 1ideways in adjacent' side walls of. the chamber extending trans versely of the said supporting wall, a clutch 'barl extending. across the chamber with'its end portions in said guidewaysspring means'yieldingly. holding said bar in spaced relation to said sup; portingwal'hfand. means fo adjusting the bar forciblyfal'ong the'guideways' in opposition to said spring means for engagement with a shoulder on the shank of: a broach in the chamber.

5. A pull head fora broaching machine'havin'g' a chamber open at one end to receive a'broach shank,1 said chamber having a wall which supports. one side of said shank, guideways in adja cent. Sidewalls of the chamber extending trans versely of the. said supporting wall,'a clutch bar extending across'thechamber with'its end por tions in said guideways; spring means yieldingly holding said bar in spaced relation to said sup porting 'wall, the face" of the bar opposing said supporting wall'of the chamber being adapted-for engaginga shoulder'on t-he'broach' shank, and a slid'e'member movable in the pull head and pro; vided with an inclined cam face engageable with the opposite 'side'of the bar for adjusting itforciblytoward said supporting wall of thefchamber to engage the'shankof a broach" therein.

1 61 A pull head for a breaching machineghav facing said clutch member to other to vary the width of said opening.

ing a chamber open at one end toreceive a broach shank, guideways in opposite side walls of the chamber extending transversely thereof, aclutch bar extending across the chamber with its end portions in said guideways, a slidemovable in the pull head'adjacent said bar, a cam block removably attached to said slide and having an inclined face engageable with the bar to shift said bar along'the guideways for engaging a shoulder on a broach shank in the chamber, and a substitute cam block of difierent depth attachable to the slide for shifting the clutch bar through a different range of 'movement in the guideways to engage a shoulder on a diiferent broach shank.

. 7. A pull head for a broaching machine having a chamber with at least oneflat wall to support a broach shank and open at one end to receive said'shank, a clutch bar extending transversely of the chamber opposite said fiat wall, means on the pull head to forcibly adjust said bar toward said flat wall for engagement with a shouldered shank of a broach, and a shim plate removably disposable on said fiat wall of the chamber to support a different broach shank in position for engagement by said clutch bar.

8. A pull head for a breaching machine having.

a chamber open at one end to receive the shank of a broach, said chamber having a fixed wall, a

. clutch member disposed opposite said fixed wall in spaced relation thereto, means to forcibly adbar guided for movement toward and-from; said wall, spring means supporting said bar yieldingly' in spaced relation to said wall, a slide movable longitudinally in the pull headprovided with a cam face operable to force the bar toward said wall into. clutching engagement with a broach shank, and a tappet extending from said slide en-- gageable with a fixed portion of the machine at one end of the stroke and operable to shift the slide longitudinally inthe pull head in a direction to release the clutch bar from its cam for releas ing the broach shank from the clutch bar.

13. A pull head for a broaching machine having a chamber of rectangular cross-section open at one end to receive a broach shank, guideways in the opposite side walls of the chamber extending transversely thereof, a clutch bar extending across the chamber withits end portions in said guideways, spring means upholding said clutch bar yieldingly in spaced relation to an opposite wall of the chamber, a slide movable longitudinally in the pull head provided with an inclined cam face operable againstsaid bar to shift the bar toward said opposite wall into clutching engagement with the broach shank, a spring pocketed in the pull head normally urging said slide in justsaid clutch member toward said wall for engagement with one side of a broach shank, and a shim plate removably disposable against said fixed wall of the chamber, said plate having a channel cradle the opposite side of the broach shank. V 9. A pull head for a broaching machine having a chamber open at one end to receive a broach shank, said chamber having a. fixed wall, a clutch member disposed opposite said fixed wall in spaced relation thereto, means to adjust said clutch member toward said wall for engagement with one side of a broach shank, and gate means onthe head at said open end of the chamber and adjustable .to vary the width of' the opening. to fit a broach shank to be entered therein.

10. A pullrhead for a breaching machine'having a chamber with at least one fiat wall to support one side of the shank of a broach, said chamber being open at one endv to receive the shank, a clutch member disposed opposite said flat wall in spaced relation thereto, means to adjust said clutch member toward said Wall for engagement with one. side ofa broach shank, and gate means on the pull head at said open end of the chamber.

defining two sides of the openingfadjacent'said fiat wall and adjustable toward and from eac 11. r A pull head for a breaching machine having a chamber open at one end to receive a broach shank, said chamber having a' fixed wall, a clutch member disposed opposite said fixed wall in spaced relation thereto, means to adjust said clutch member toward said wall for engagement with 7 oneside of a broach shank, and a pair of gate members mounted on the head at said open end and slidably adjustable toward and from each other to vary the width of the opening, together with means forr'securing them at any desired position of such adjustment.

12. A pull head for a breaching machine having a chamber open at one end to receive a broach shank, said chamber havinga fixed wall, a clutch the direction to so shift the clutch bar, and a handle on the slide operable for moving it in the opposite direction to permit the aforesaid springs to shift the bar to release position.

14. In combination with a broach having a 1 shank with a transverse shoulder at only one side of said shank, a pull head having a chamber open 7 at one end to receive said shank, said pull head providing a part engageable with said shoulder of the shank and an oppositely disposed part tov engage the opposite side of the shank, one of said parts being fixed, and positive means for adjusting the other of said parts toward and from the fixed part for holding engagement with the shank.

'15. In combination with a broach having a shank with a transverse shoulder, at one side of said shank, a pull head having a chamber open at one end to receive said shank, said pull head providing a partengageable with said shoulder of the shank and an oppositely disposed part to gagement with the shouldered shank of the broach. j a

16. A pull head for a broaching machine having a chamber with at least one flat wall to support a broach shank and open at one 'end to receive said shank, a clutch bar extending transversely of the chamber oppositesaid fiat wall, means on the pull head to forcibly adjust said bar toward said flat wall for engagement with a shouldered shank of a broach, a set of shim plates each dis posable on said flat wall of the chamber to support a broach shank therein, the pull head having a hole extending through its said flat wall with a bolt to fit therein, each shim plate having, a threaded hole engageable with said bolt and a clearance opening dimensioned to pass the bolt, whereby one or more shim plates of theset may be secured in the chamber by the bolt against said fiat wall with the remaining plate or plates of the set carried on the bolt between its head and the outer face of said wall, said bolt extending through the clearance openings of all but one plate of the set.

17. A pull head for a broaching machine hav ing a chamber with at least one flat wall to support a broach shank and open at one end to re ceive said shank, a clutch bar extending transversely of the chamber opposite said flat wall, means on the pull head to forcibly adjust said bar toward said fiat wall for engagement with a shouldered shank of a broach, a set of shim plates each of different thickness and disposable on said flat wall of the chamber to support a broach shank therein, the pull head having a pair of holes extending through its said flat wall with bolts to fit therein, each shim plate having a pair of threaded holes engageable with said bolts and a pair of clearance openings dimensioned to pass the bolts, whereby one or more shim plates of the set may be secured in the chamber by the bolts against said flat wall with the remaining plate or plates of the set carried on the bolts between their heads and the outer face of said wall, said bolts extending through the clearance openings of all but the uppermost plate of the set.

18. A pull head for a broaching machine having a chamber with at least one fiat wall to support a broach shank and open at one end to receive said shank, a clutch bar extending tran'sversely of the chamber opposite said flat wall, means on the pull head to forcibly adjust said bar toward said flat wall for engagement with a shouldered shank of a broach, a set of shim plates each disposable on said flat wall of the chamber to support a broach shank therein, the

pull head having a hole extending through its said flat wall with a bolt to fit therein and long enough to extend through said wall and through all the shim plates of the set, whereby one or more shim plates of the set may be secured in the chamber of the pull head by said bolt extending through said wall of the chamber with the remaining plate or plates of the set carried on the bolt outside the chamber.

19. In combination with a broach having a shank formed with a flat side and with a transverse shoulder at the side of the shank opposite said flat side, a pull head having a chamber with a flat wall and open at one end to receive said shank with its fiat side engaging said flat wall, a clutch member movable in the chamber toward and from said flat wall and means on the pull head for adjusting said clutch member positively toward said wall into position for engagement with said shoulder of the shank.

20. In combination with a broach having a shank with a transverse shoulder at only one side of said shank, a pull head having a chamber open at one end to receive said shank, said pull head including a clutch member movable into engagement with said shoulder and an oppositely disposed fixed part engageabl with the opposite side of said shank, and means for positively adjusting said clutch member into holding engagement with said shoulder.

FRANCIS J. LAPOINTE. 

